JP3452295B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus, and more particularly, to an image forming apparatus using a two-component developer composed of toner and carrier without using a toner sensor. The present invention relates to means for keeping the toner density constant.

[0002]

2. Description of the Related Art There are various known image forming systems for image forming apparatuses such as copying machines, printers, and facsimile machines, but since image quality and deterioration of images formed on recording paper with time are small. In recent years, an electrophotographic image forming apparatus has been exclusively used. The electrophotographic image forming apparatus uses a two-component developer of toner and carrier to visualize the toner by adsorbing the toner on the electronic latent image formed on the surface of the photoconductor. Is transferred and fixed on the recording paper. At this time, the toner of the above-mentioned developer is transferred to the recording paper and consumed as the image is formed. Therefore, it is necessary to replenish the toner on a regular basis or when the toner decreases to a predetermined amount or less. Further, the toner supplied is uniformly mixed with the above carrier and is configured to be conveyed to the surface of the photoconductor. If the toner density is non-uniform, the image density transferred to the recording paper is uneven. , The image quality is significantly degraded.
In this type of image forming apparatus, generally, an image forming unit is provided in the developing device in the vicinity of the photoconductor, and the image forming unit is provided with a mechanism for stirring and mixing the toner and the carrier. There is. Further, in order to keep the image quality constant, it is necessary that the above two developers are uniformly mixed at a required concentration, and moreover, the concentration should be uniform over the front surface of the photoconductor surface. Conventionally, in order to keep the mixing ratio of the toner and the carrier, that is, the toner concentration uniform, toner concentration sensors are arranged at the toner stirring portion of the developing device and at various places in the vicinity of the photoconductor, and the toner output is monitored while monitoring the output of each sensor. The amount of supply was controlled.

[0003]

However, the toner supply amount control means in the conventional image forming apparatus as described above has the following problems. That is, since it is necessary to arrange a large number of toner concentration sensors, the number of parts increases, which leads to an increase in size and cost of the apparatus. Also,
With the density detecting means using the toner sensor, only the density in the vicinity of the sensor is detected, so that accurate density detection is difficult. Further, since it takes time for the replenished toner to reach all of the vicinity of the toner sensor dispersed in a wide range, toner is intermittently replenished little by little in order to prevent excessive toner replenishment. It was necessary to perform complicated control of agitating while determining the replenishment amount thereafter based on the output of the toner sensor of each part. Therefore, in general, such a replenishment control means cannot avoid a certain degree of density fluctuation at the time of replenishing the toner, and conventionally, the biggest problem has been how to reduce the fluctuation. In particular, in an image forming apparatus equipped with a means for recovering toner once attached to the surface of the photoconductor by a cleaning means and reusing it, the above control becomes more complicated, and image quality deterioration due to density fluctuation cannot be avoided. The present invention has been made to solve the problems relating to the toner density control of the conventional image forming apparatus as described above, and it is possible to reduce the size and cost of the apparatus by eliminating the arrangement of many toner sensors. It is an object of the present invention to provide an image forming apparatus that can reduce the amount of toner and that has less fluctuation in toner density by considering the supply of recycled toner.

[0004]

In order to achieve the above object, in the image forming apparatus of the present invention, the invention of claim 1 is an electrostatic latent image formed by irradiating a photosensitive member with laser light in dot units. with visualized by a two-component developer comprising the image of toner and carrier, transferring it to the recording paper, a photoreceptor
Remaining toner remaining in the product is recycled as a developer again
In the electrophotographic image forming apparatus provided with a means for conveying the developer to the photosensitive member while stirring the developer, the writing area of the photosensitive member is divided into a required number, and the laser irradiation dot number for each divided area is set. Counting means; means for accumulating the number of dots in the entire writing area based on the counted number of dots; means for storing the toner consumption amount per dot; and the stored toner consumption amount per dot and means for estimating an amount of toner consumption from the above integration result, sensitive
Unit time by counting the number of dots in the writing area of the optical body for a predetermined time
Means to calculate the average number of dots per interval and this average
From the number of dots and the amount of toner recycled per dot
A means to estimate the amount of toner recycled per unit time
And the toner consumption calculated above
The amount of toner to be replenished is determined based on the result of subtracting the amount of toner
And means for determining . According to a second aspect of the invention, in the image forming apparatus according to the first aspect, humidity detection is performed.
Means, humidity, and toner consumption per dot
Means to store, the humidity during use and the humidity stored above
It is characterized in that it comprises means for correcting the amount of toner to be replenished in relation to the amount of toner consumed .

Since the present invention is configured as described above, in the invention of claim 1, the recycled toner recovered from the photoconductor is used.
It is configured to estimate the amount of replenishment toner considering
Image of a type that reuses the toner remaining on the photoconductor
Even in the forming device, the excessive supply of toner is prevented, and
It is possible to keep the toner density constant. Claim 2
Of the present invention, the humidity sensor and the relationship between the humidity and the toner consumption amount.
The toner consumption is calculated according to the stored means and the environmental humidity.
Since it is configured to correct the output value, humidity fluctuations are taken into consideration.
It is possible to determine the toner replenishment amount.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments of the present invention shown in the drawings. FIG. 3 is a sectional configuration diagram showing an example of an image forming unit of an image device to which the present invention is applied, and FIG. 4 is a perspective external view thereof. The image forming unit 1 is detachably attached to the main body of the image forming apparatus (not shown) in the direction of arrow A in FIG. 4. When the image forming unit 1 is attached to the image forming apparatus, the toner replenishing bottle 2 is placed in the vicinity thereof. Becomes The image forming apparatus is, for example, a printer, a facsimile, a copying machine or a composite machine thereof. The image forming unit 1 shown in this example includes a unit case 3 as shown in FIGS. 3 and 4, and various functional blocks incorporated therein as described later. Unit case 3
Includes a case body 4, a case cover 5 attached to the upper part thereof, a developing case cover 6, and an upper cover 7 of the developing case, and the developing case cover 6 has an opening 8. The opening 8 is not shown in FIG. 4, but the developing cartridge 9 shown in FIG.
Is covered by.

A drum-shaped photosensitive member 1 which is an example of an image carrier on which an electrostatic latent image is formed in the unit case 3.
0 and a charging roller 11 as an example of a charging device are assembled in parallel with each other and in pressure-contact with each other. For the sake of clarity, only part of the charging roller 11 is
Moreover, it is drawn in a state of being separated from the photoconductor 10. Photoconductor 1
In the vicinity of 0, to rotate in synchronization with the photosensitive drum,
The developing sleeve 12 is pivotally supported, and a strong magnet 13 is fixed inside the developing sleeve 12. The developing sleeve 12 is located inside the developer chamber 90, and screw-like stirring members 14 and 15 are arranged in parallel with the developing sleeve 12 as shown in FIG. It is arranged so as to rotate by a drive mechanism that does not contain a two-component developer 16 in which toner and carrier are mixed. On the other hand, a transfer roller 17 is attached to the lower portion of the photoconductor 10 so as to rotate in the arrow direction in synchronization with the photoconductor. Although other members are also shown in the drawing, since they are well known as general image forming apparatuses, detailed description thereof will be omitted, and an image forming mechanism will be briefly described.

In the above structure, during the image forming operation,
While the photoconductor 10 is rotated in the clockwise direction as shown in FIG. 3 by a drive unit (not shown), charge removal light L1 from a charge remover (not shown) is also emitted, and this light causes the potential of the photoconductor surface to fall, for example, from 0 to It is averaged to a reference potential of about -150V. On the other hand, the charging roller 11 is the photosensitive member 10.
It comes into pressure contact with the surface of the photoconductor and rotates with the rotation of the photoconductor, but a negative charge is applied by a power supply device (not shown),
This charges the surface of the photoconductor 10 to, for example, about -1100V. In this state, when the drum surface of the photoconductor 10 is irradiated with the laser beam L2 guided from the document reading device, the potential of the portion irradiated with the laser beam becomes about 0 to -290V. That is, when the amount of laser light changes according to the original image, the potential on the surface of the photoconductor changes accordingly, and an electrostatic latent image is formed. In the present invention, as a method for controlling a laser beam for reading a document and irradiating the photoconductor,
A means for controlling the amount of laser light for each dot and forming an electrostatic latent image on the surface of the photoconductor as an aggregate of dots is adopted.
Such an exposure method is generally adopted in a recent digitized image forming apparatus and is suitable for application of the present invention.

On the other hand, a developing bias voltage of, for example, about -800 V is applied to the developing sleeve 12 of the developing unit 1, and the toner adhered to the developing sleeve 12 is also given the same potential. It electrostatically transfers to and adheres to the electrostatic latent image. As a result, the electrostatic latent image on the surface of the photoconductor is visualized as a toner image. Further, when the photoconductor 12 rotates and reaches the position where it abuts the transfer roller 17, the toner image is transferred onto the recording paper 19 conveyed along the guide plate 18. A transfer bias potential is applied to the transfer roller 17, so that the toner image on the photoconductor is easily transferred to the recording paper. The toner image transferred to the recording paper is fused and fixed on the surface of the recording paper by heat and pressure.
The developing unit 1 accommodates a two-component developer having a carrier made of fine iron balls and toner, and is conveyed while being agitated inside the developer chamber 90 by two agitating members described later. As the image is formed on the recording paper, the amount of toner decreases and the toner density decreases.
It is necessary to replenish the toner periodically or whenever the toner concentration falls below a predetermined value. As described above, various problems have occurred because toner density sensors have conventionally been arranged at various places as the method. Therefore, in the present invention, the toner replenishment control is performed as follows on the premise that the laser light guided from the document reading device to the photoconductor is controlled in dot units.

FIG. 1 is a schematic configuration diagram showing a main part structure of a developing unit according to the present invention, and FIG. 2 is a diagram for explaining control of toner replenishment. In this example, the first agitating members 21 and 22 are provided inside the developing unit in parallel with the developing sleeve 12 described above, and the developer is counterclockwise in the first agitating member 21 as indicated by an arrow in the figure. Direction, and the second stirring member 22 circulates in the clockwise direction, and the recycled toner collected from the photoconductor and the toner newly supplied are mixed in the left extension portion of the first stirring member 21. ing. That is, the toner circulated in the developer chamber, the recycled toner, and the newly supplied toner come together at the left end portion of the first stirring member. In the first embodiment described below, the case of controlling by ignoring the amount of recycled toner is shown.
The recycled toner will be described in the second embodiment. Now, as shown in the figure, the maximum writing width of the photoconductor 10 is set to L, this section is divided into N blocks, and this L / N is set as one unit width. ) Is counted. FIG. 2 shows the photoreceptor 1
It is a figure which shows the range of the pixel number count time for every L / N with respect to 0 and the maximum writing width L of the 2nd stirring member 22 which adjoins this.

Assuming that the writing time of each L / N is β, the writing start time of the block to be written after αt seconds from the start is αt, the writing start time of the next block is αt + β, and thereafter, αt + 2.
β, αt + 3β, ... Accordingly, the write start time of the n-th block is αt + (n-1) β , write end time ing the [alpha] t + N.beta. As this, with the passage of time t, it counts the number of write pixels in each moving position of each block position, the time series records respectively, integrates the number of total write pixel of the entire maximum write width To do. Further, if the toner consumption amount per pixel (dot) is multiplied by the total number of pixels accumulated, the total toner consumption amount can be calculated. That is, the supply amount VH is
If the number of pixels is P and the toner consumption amount per pixel is D, it can be expressed by the formula VH = P.D. According to this method, the toner consumption amount can be calculated without using a toner concentration sensor as in the conventional case, and if toner is replenished according to the consumption amount, a toner amount that is close to the actually consumed toner amount is replenished. Therefore, it is possible to always maintain a uniform toner concentration, which is effective in simplifying the apparatus and reducing the cost.

Next, as a modified embodiment of the present invention, the case of using recycled toner will be described. That is, when the toner collected from the photoconductor is to be returned to the stirring unit of the developing unit again, the amount of recycled toner is calculated, and the amount is subtracted from the toner consumption amount described above. As a method of calculating the amount of recycled toner, for example, with respect to the maximum writing width L, the number of pixels is counted for a certain period of time (T seconds), the total number of pixels in this period is S, and the average amount of recycled toner per unit time is Vr. Then, VR = {S ・ D (1
-Transfer rate / 100)} / T (g / sec). Therefore, a means for counting and storing the number of pixels for the L width for T time and a means for calculating the average recycled toner amount per unit time from this result are provided, and the number of pixels is counted for a certain period of time and divided by time. Then, the average amount of recycled toner can be obtained. Therefore, not good if determining replenishment amount this result is subtracted from the toner supply amount described above. Further, the present invention may be modified as follows. For example, the amount of toner used varies depending on the humidity, the amount of toner used decreases when the humidity is low, and the amount of toner used tends to increase when the humidity is high. Therefore, if a humidity sensor is provided in the main body, the humidity and the toner usage amount per dot are stored in memory, and the means for correcting the toner consumption amount according to the environmental humidity change is provided, the toner can be more accurately The concentration can be controlled. The above processing can be realized as a software program by using the CPU or peripheral storage device mounted in the image forming apparatus, but a CPU or storage device may be specially provided for realizing the present invention. Needless to say.

[0013]

As described above, according to the present invention, in an electrophotographic image forming apparatus, means for conveying a developer to a photosensitive member while stirring and dividing a writing area of the photosensitive member into a required number and Means for counting the number of laser-irradiated dots for each divided area, means for accumulating the counted number of dots in the entire writing area, means for storing the toner consumption amount per dot, and A means for estimating the toner consumption amount from the transport moving speed, the stored toner consumption amount per dot and the integrated result, and a means for replenishing the toner amount determined based on the estimated toner amount are provided. Therefore, it is possible to maintain a constant toner density without complicated control by providing a large number of toner sensors as in the prior art, which is effective in reducing the size and cost of the apparatus. . Furthermore, since the amount of toner that is extremely close to the amount of toner actually consumed will be replenished,
It is possible to form a high-quality image by reducing fluctuations in toner density and excessive or insufficient replenishment. The second means is configured to calculate the amount of toner to be replenished by adding recycled toner collected from the photoconductor to the first means. It is possible to keep the toner concentration constant without fear of excessive replenishment. In the third means, the toner replenishment amount is determined in consideration of the fluctuation of the toner consumption amount with respect to the humidity fluctuation. Therefore, even if the humidity of the environment fluctuates, the consumption amount close to the actually consumed toner amount is obtained. Can be replenished in quantity. Therefore, even when the humidity changes, there is no fear of excessive or insufficient replenishment of toner.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of main parts of an image display device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining one embodiment of the present invention and is a write timing diagram for each divided write area.

FIG. 3 is a cross-sectional view of essential parts for explaining an embodiment of an image forming apparatus to which the present invention is applied.

FIG. 4 is a perspective external view for explaining an embodiment of an image forming apparatus to which the present invention is applied.

[Explanation of symbols]

1 ... Image forming unit, 2 ... Toner supply bottle, 3 ... Unit case, 4 ... Case body, 5 ... Case cover, 6
... developing case cover, 7 ... upper cover, 8 ... opening,
9 ... Developing cartridge, 10 ... Photoconductor, 11 ... Charging roller, 12 ... Developing sleeve, 13 ... Magnet, 14,
15, 21, 22 ... Stirring member, 16 ... Two-component developer,
17 ... Transfer roller, 18 ... Guide plate, 19 ... Recording paper, 23 ... Recycled toner supply port.

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-6-138769 (JP, A) JP-A 63-144377 (JP, A) JP-A 7-287443 (JP, A) JP-A 61- 129669 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 15/08 114 G03G 15/00 550 G03G 21/00 510

Claims (2)

(57) [Claims] 1. A visualized by a two-component developer composed of toner and carrier to an electrostatic latent image formed by irradiation with dots the laser beam to the photosensitive member, when transferring it to the recording paper co
In addition, the toner remaining on the photoconductor is collected and reused as a developer.
In an electrophotographic image forming apparatus equipped with a means for recycling, a means for conveying the developer to the photoconductor while stirring it, and dividing the writing area of the photoconductor into the required number and the number of laser irradiation dots for each divided area. For counting the total number of dots in the writing area based on the counted number of dots, a means for storing the toner consumption amount per dot, and a toner consumption amount for each dot stored above. And means for estimating the toner consumption amount from the integration result,
Counts the number of dots in the writing area of the photoconductor for a predetermined time
This means to calculate the average number of dots per hour
The number of dots and the amount of toner recycled per dot
To estimate the amount of toner recycled per unit time from
And the toner consumption of the above estimated toner consumption
Toner amount to be replenished based on the result of subtracting the icle amount
An image forming apparatus comprising: a determining unit. 2. The image forming apparatus according to claim 1, wherein
Degree detection means, humidity and toner consumption per dot
The means for storing the relationship between
To compensate for the amount of toner to be replenished, consider the relationship between humidity and toner consumption.
An image forming apparatus comprising the positive to means.